Clarify docstring and add warning
Clarify docstring and add warning

This will alert the user whenever they attempt a findMany request and
inform them that they need to implement a custom filter on the DRF side
for it to work properly.

dustinfarris/ember-django-adapter,stefanpenner/ember-django-adapter,benkonrath/ember-django-adapter,benkonrath/ember-django-adapter,kevinwmerritt/ember-django-adapter,holandes22/ember-django-adapter,stefanpenner/ember-django-adapter,Lightmatter/ember-django-adapter,gannetson/ember-django-adapter,kevinlondon/ember-django-adapter,jpadilla/ember-django-adapter,holandes22/ember-django-adapter,Lightmatter/ember-django-adapter,kevinwmerritt/ember-django-adapter,gannetson/ember-django-adapter,jpadilla/ember-django-adapter,kevinlondon/ember-django-adapter,dustinfarris/ember-django-adapter